(a) Field of the Invention
Embodiments of the present invention relate generally to flat panel displays. More specifically, embodiments of the present invention relate to a flat panel display device using an oxide semiconductor and a method of manufacturing the same.
(b) Description of the Related Art
In general, a thin film transistor (TFT) is used as a switching element for independently driving each pixel in a flat panel display such as a liquid crystal display, an organic light emitting display or the like. A thin film display panel including such a thin film transistor typically includes a gate line for transferring a gate signal to the thin film transistor, a data line for transferring signals such as data signals, and a pixel electrode connected to the thin film transistor.
The thin film transistor also typically includes a gate electrode connected to the gate line, a source electrode connected to the data line, a drain electrode connected to a pixel electrode, and a semiconductor layer disposed on the gate electrode between the source electrode and the drain electrode. In this manner, the TFT transfers the data signal from the data line to the pixel electrode according to the gate signal from the gate line.
The semiconductor is an important factor for determining characteristics of the thin film transistor. Amorphous silicon is mainly used for the semiconductor, but has limitations in manufacturing high performance thin film transistors since amorphous silicon has low charge mobility. Further, when polysilicon is used, it is easier to manufacture high performance thin film transistors due to high charge mobility. However, there is a limitation in manufacturing large thin film transistor display panels due to higher cost and lower uniformity.
Accordingly, research is currently being conducted on thin film transistors using oxide semiconductors having higher electron mobility and a higher on/off rate of current than amorphous silicon, and having lower cost and higher uniformity than the polysilicon.
In particular, some of this research focuses on using zinc oxide (ZnO), tin oxide (SnO2), zinc-tin oxide (ZnSnO) and the like for the oxide semiconductor. However, since characteristics of thin film transistor and their etching characteristics may vary depending on the composition of component materials forming the oxide semiconductor, the manufacture of display devices using oxide semiconductors faces challenges.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.